Chemiluminescence is the result of a chemical reaction which creates light with little or no heat involved. In the reaction, an excited intermediate molecule emits photons of light as it decays. In theory, one molecule of a reactant can produce one photon of light. In actuality, most of these reactions rarely have more that 1% quantum efficiency, which is the ratio of photons to molecules. Luminol is a heterocyclic compound. When mixed with the oxidizing agent potasium ferricyanide/hydrogen peroxide, the luminol goes through a chemiluminescence reaction where it obtains an excited state before decaying and releasing photons of light. The purpose of this experiment is to look at the effect of combining different amounts of a luminol mixture and potasium ferricyanide/hydrogen peroxide mixture on light intensity.
Procedure
We dissolved .05g of luminol in 2.5 mL of 10% aqueous sodium hydroxide solution and 22.5 mL of water, this solution was labeled, solution A.
We then mixed 20 mL of 3% aqueous potassium ferricyanide, 20 mL of 3% hydrogen peroxide and 160 mL of water. This was designated solution B.
Next we diluted 25 mL of solution A with 175 mL of water. In a darkened area of the laboratory, we poured this solution simultaneously with solution B, into a funnel leading to a 1-L Erlenmeyer Flask. We stirred the contents and observed. As the color faded, we added 3 mL of 10% aqueous base, and then mixed further. We put a light sensor inside the flask to calculate the amount of light. The sensor was connected to the Legger Pro Software and Venir Lab Pro.
These steps were repeated twice more, the only variable was the amount of luminol used everything else remained constant. In the second trial .1g of luminol was used. The third trial consisted of .15g of luminol.
Results
In each trial the mixture of each solution created a blue/green light lasting for a few short amounnt of time (2 seconds-7 seconds). Of the three trials, the first trial (.05 grams of luminol) created the longest lasting and most illuminated light. The instrument used to measure the light intensity was unable to produce an accurate reading.
Conclusions
From our results, we found that the less luminol used made for a more illuminated substance. However, this could be due to the aging of the luminol, because we believed that the luminol would increase the length of light. The solutions for the first trial were left out longer than the other two solutions which could have caused an increase in light. To improve this experiment a fresher substance of luminol should be used. And a better light detector that can register the light quicker and more accurately.
Chemiluminescence
Jared, Avi
Introduction
Chemiluminescence is the result of a chemical reaction which creates light with little or no heat involved. In the reaction, an excited intermediate molecule emits photons of light as it decays. In theory, one molecule of a reactant can produce one photon of light. In actuality, most of these reactions rarely have more that 1% quantum efficiency, which is the ratio of photons to molecules. Luminol is a heterocyclic compound. When mixed with the oxidizing agent potasium ferricyanide/hydrogen peroxide, the luminol goes through a chemiluminescence reaction where it obtains an excited state before decaying and releasing photons of light. The purpose of this experiment is to look at the effect of combining different amounts of a luminol mixture and potasium ferricyanide/hydrogen peroxide mixture on light intensity.
Procedure
We dissolved .05g of luminol in 2.5 mL of 10% aqueous sodium hydroxide solution and 22.5 mL of water, this solution was labeled, solution A.
We then mixed 20 mL of 3% aqueous potassium ferricyanide, 20 mL of 3% hydrogen peroxide and 160 mL of water. This was designated solution B.
Next we diluted 25 mL of solution A with 175 mL of water. In a darkened area of the laboratory, we poured this solution simultaneously with solution B, into a funnel leading to a 1-L Erlenmeyer Flask. We stirred the contents and observed. As the color faded, we added 3 mL of 10% aqueous base, and then mixed further. We put a light sensor inside the flask to calculate the amount of light. The sensor was connected to the Legger Pro Software and Venir Lab Pro.
These steps were repeated twice more, the only variable was the amount of luminol used everything else remained constant. In the second trial .1g of luminol was used. The third trial consisted of .15g of luminol.
Results
In each trial the mixture of each solution created a blue/green light lasting for a few short amounnt of time (2 seconds-7 seconds). Of the three trials, the first trial (.05 grams of luminol) created the longest lasting and most illuminated light. The instrument used to measure the light intensity was unable to produce an accurate reading.
Conclusions
From our results, we found that the less luminol used made for a more illuminated substance. However, this could be due to the aging of the luminol, because we believed that the luminol would increase the length of light. The solutions for the first trial were left out longer than the other two solutions which could have caused an increase in light. To improve this experiment a fresher substance of luminol should be used. And a better light detector that can register the light quicker and more accurately.
References
Unknown author. Chemiluminescence. 28 May 2008. <http://spot.pcc.edu/~gbackes/ORGANIC/CH%20243/Synthesis.of.Luminol.htm>
Hart, Harold, and Leslie E. Craine. Organic Chemistry: A Short Course. Boston: Houghton Mifflin Company, 1995.